Catheter with a pre-shaped distal tip

ABSTRACT

Catheters having a pre-shaped tip configuration are disclosed. A catheter in accordance with an illustrative embodiment of the present invention can include an elongated tubular shaft equipped with a distal tip section having a pre-shaped tip configuration that can be used to facilitate tracking of the device through particular locations of the vasculature. The catheter may include a number of features that transition the stiffness and flexibility characteristics of the device and provide a means to radiographically visualize the catheter within the body.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/577,841 filed Oct. 13, 2009, which is a continuation of U.S.application Ser. No. 10/970,204 filed Oct. 21, 2004, now U.S. Pat. No.7,621,904.

FIELD

The present invention relates generally to the field of medical devices.More specifically, the present invention pertains to catheters having apre-shaped distal tip.

BACKGROUND

Medical catheters such as guide catheters are utilized in a wide varietyof interventional procedures to facilitate advancement of therapeuticdevices to target locations within the body. In applications involvingthe neurovasculature, for example, such devices can be used inconjunction with a guidewire to advance an endovascular coil,atherectomy catheter, drug delivery catheter, or other such therapeuticdevice to select vascular regions within the body to treat vasculardisease.

In certain applications, it may be desirable to impart a particularshape to the catheter tip to facilitate tracking of the catheter throughtortuous anatomy, or to advance the catheter beyond a lesion or otherobstruction within the body. In the treatment of aneurysms, for example,such shaped catheter tips can be used to reach select vascular regionswithin the body such as the anterior communicating artery or theposterior communicating artery. Once positioned, such tip shapes canalso be used to maintain the stability of the catheter at the site ofthe aneurysm by using the tip shape to stabilize a portion of thecatheter body against the vessel wall while maintaining the tip at thesite of the aneurysm.

Shaping of catheter tips is typically accomplished in a clinical orsurgical setting by bending the tip manually to a desired shape, andthen setting the shape within the aid of shaping equipment. In asteam-shaping process, for example, the shape of the catheter tip istypically formed by the physician bending the tip to a particular shapeand then steaming the tip to impart the desired shape. While a number ofdifferent shapes can be formed in this manner, such techniques oftenrequire the physician to perform additional steps in preparation for theprocedure, thus increasing the time required to perform theinterventional procedure. Moreover, the efficacy of such techniques isoften dependent on the skill of the physician and the precision of theequipment employed.

SUMMARY

The present invention pertains to catheters having a pre-shaped distaltip. A catheter in accordance with an illustrative embodiment of thepresent invention can include an elongated tubular shaft having aproximal shaft section, an intermediate shaft section, a distal shaftsection, and an interior lumen adapted to slidably receive a guidewire.Each of the proximal, intermediate, and distal shaft sections mayinclude an outer layer of material adapted to transition the stiffnessof the elongated tubular shaft along its length. In certain embodiments,for example, each of the shaft sections may comprise a material having adifferent durometer that transitions the stiffness of the shaft from arelatively stiff configuration along the proximal shaft section to arelatively flexible configuration along the distal shaft section. Insome embodiments, the shaft may include an inner layer or coating oflubricious material adapted to reduce friction within the interiorlumen. Other features relating to the performance and radiopacitycharacteristics of the catheter are also described herein.

The catheter can include a distal tip section having a pre-shaped tipconfiguration that can be used to facilitate tracking of the devicethrough particular locations of the vasculature. In certain embodiments,for example, such pre-shaped tip configuration can be employed tofacilitate insertion of the catheter at locations within the body suchas the anterior communicating artery, the posterior communicatingartery, the ophthalmic artery, the middle cerebral artery, and/or thesuperior cerebellar artery. The distal tip section can be pre-shapedinto any number of desired tip configurations, including, for example,an angled tip configuration, a curved tip configuration, a J-shaped tipconfiguration, a C-shaped tip configuration, and an S-shaped tipconfiguration. In use, such pre-shaped tip configurations may reduce theshape variability that can result from shaping the catheter tip manuallyin a clinical or surgical setting, and may reduce the overall timerequired to perform the interventional procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a catheter in accordance with an exemplaryembodiment of the present invention;

FIG. 2 is a longitudinal cross-sectional view showing a distal portionof the catheter of FIG. 1 in greater detail;

FIG. 3 is a side plan view showing the catheter of FIG. 1 equipped witha distal tip section in accordance with an illustrative embodimenthaving an angled tip configuration;

FIG. 4 is a side plan view showing the catheter of FIG. 1 equipped witha distal tip section in accordance with an illustrative embodimenthaving a curved tip configuration;

FIG. 5 is a side plan view showing the catheter of FIG. 1 equipped witha distal tip section in accordance with an illustrative embodimenthaving a J-shaped tip configuration;

FIG. 6 is a side plan view showing the catheter of FIG. 1 equipped witha distal tip section in accordance with an illustrative embodimenthaving a C-shaped tip configuration;

FIG. 7 is a side plan view showing the catheter of FIG. 1 equipped witha distal tip section in accordance with an illustrative embodimenthaving an S-shaped tip configuration; and

FIG. 8 is a side plan view of an illustrative shape retention mandrelfor use with a catheter of the present invention.

DETAILED DESCRIPTION

The following description should be read with reference to the drawings,in which like elements in different drawings are numbered in likefashion. The drawings, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope of theinvention. Although examples of construction, dimensions, and materialsare illustrated for the various elements, those skilled in the art willrecognize that many of the examples provided have suitable alternativesthat may be utilized.

FIG. 1 is a plan view of a catheter 10 in accordance with an exemplaryembodiment of the present invention. Catheter 10, illustratively a guidecatheter for use in neurovascular and peripheral interventions, includesan elongated tubular shaft 12 having a proximal shaft section 14, anintermediate shaft section 16, and a distal shaft section 18. The shaft12 may define an interior lumen 20, which in the illustrative embodimentof FIG. 1 extends from a proximal end 22 of the catheter 10 to a distalend 24 thereof. In certain embodiments, the interior lumen 20 of theshaft 12 can be configured to slidably receive a guidewire 26 that canbe used to track other therapeutic devices to target locations withinthe body. In certain applications, for example, catheter 10 can be usedto facilitate advancement of the guidewire 26 to select vascular regionswithin the body such as the anterior communicating artery or posteriorcommunicating artery for the treatment of aneurysms.

The proximal shaft section 14 can include a hub and strain reliefassembly 28 that can be used as an aid to manipulate the catheter 10from a location outside of the body. The hub and strain relief assembly28 may include a main body 30 having a number of fins 32 that can beused to improve gripping and to facilitate labeling for productidentification, and a strain relief member 34 adapted to provideadditional column strength and rigidity to the proximal shaft section14. A second strain relief member (not shown) may be disposed on theshaft 12 distally of strain relief member 34 to provide additionalstrain relief to the proximal shaft section 14 of the catheter 10, ifdesired.

The length of the various shaft sections 14,16,18 may vary depending onthe particular location within the body to be traversed, and theperformance characteristics (e.g. flexibility, column strength, etc.)desired in the catheter 10. In certain embodiments, for example, theproximal shaft section 14 may be made available in 80 cm, 105 cm, and125 cm embodiments, although other lengths are possible. In suchembodiments, the overall length of the catheter 10 may be 105 cm, 130cm, and 150 cm, respectively, which is typical for catheters employed inneurovascular and/or peripheral interventions. It should be understood,however, that the length of the catheter 10 may vary to permit thecatheter 10 to be used at other locations within the body and/or toperform other types of interventional procedures.

FIG. 2 is a longitudinal cross-sectional view showing a distal portionof the catheter 10 of FIG. 1 in greater detail. As can be seen in FIG.2, the shaft 12 can include an inner layer or coating 36 of lubriciousmaterial that extends along all or a portion of the catheter 10. Incertain embodiments, for example, the inner layer or coating 36 maycomprise a hydrophilic polymer material that reduces friction within theinterior lumen 20. An example of such lubricious material ispolytetrafluoroethylene (PTFE), which is commercially available fromDupont under the trademark TEFLON®. Other materials such as polyethylene(PE), polypropylene (PP), polyvinylchloride (PVC), ethylvinylacetate(EVA), polyurethanes, polyamides, polyethyleneteraphthalate (PET),ethylene-chlorofluoroethylene (ECTFE), fluorinated ethylenepropylene(FEP), polychlorotrifluoroethylene (PCTFE), polyvinylfluoride (PVF),polyvinylidenefluoride (PVDF), and their mixtures and/or copolymersthereof may also be employed, if desired.

The interior lumen 20 may be uniform along the proximal, intermediate,and distal shaft sections 14,16,18 of the catheter 10, or may vary indimension at one or more locations along the length of the shaft 12, ifdesired. In the illustrative embodiment depicted in FIG. 2, for example,the interior lumen 20 is substantially uniform along the entire lengthof the shaft 12, having an inner diameter D_(I) in the range of about0.012 to 0.021 inches, and more specifically 0.014 to 0.019 inches,which is sufficiently large to permit many conventional guidewires to beinserted and advanced through the interior lumen 20. The inner diameterD_(I) may be made larger or smaller, however, to permit other sizedguidewires and/or other intravascular devices to be advanced through theinterior lumen 20, if desired.

The shaft 12 may further a number of outer layers that can be used totransition the stiffness of the shaft 12 from a relatively stiffconfiguration along the proximal shaft section 14 to a relativelyflexible configuration along the distal shaft section 18. In certainembodiments, for example, each of the proximal, intermediate, and distalshaft sections 14,16,18 may comprise a different polymeric materialadapted to impart a desired strength, flexibility, hardness, and/orother desired characteristic to the catheter 10. In the illustrativeembodiment of FIG. 2, for example, proximal shaft section 14 may includean outer layer segment 38 of material having a relatively high durometerwhereas the distal shaft section 18 may include an outer layer segment40 of material having a relatively low durometer. In one suchembodiment, the outer layer segment 38 of the proximal shaft section 14may comprise a relatively stiff polymeric material such as PEBAX® 7233whereas the outer layer segment 40 of the distal shaft section 18 maycomprise relatively flexible polymeric material such as PEBAX® 2533. Theouter layer segments 38,40 may each comprise a single polymer, multiplepolymers, or a blend of polymers, as desired.

To further transition the stiffness along the length of the shaft 12,the intermediate shaft section 16 can include one or more outer layersegments comprising a material having a durometer that is intermediateto that of the proximal and distal shaft sections 14,18. In oneillustrative embodiment, for example, the intermediate shaft section 16may include a first outer layer segment 42 of PEBAX® 5533 that spans thelength of the shaft 12 from a first location 44 to a second location 46thereof. A second outer layer segment 48 of PEBAX® 4033 can be providedalong the portion of the intermediate shaft section 16 extending fromthe second location 46 to a third location 50 thereof. While theillustrative embodiment of FIG. 2 shows the use of two outer layersegments 42,48 along the length of the intermediate shaft section 16, itshould be understood that a greater or lesser number of segments can beprovided, if desired. Moreover, as with the outer layer segments 38,40of the proximal and distal shaft sections 14,18, the outer layersegments 42,48 of the intermediate shaft section 16 can include a singlepolymer, multiple polymers, or a blend of polymers, as desired.

In certain embodiments, an intermediate layer of material can beprovided between the inner layer 36 and the various outer layerssegments 38,40,42,48 of the shaft 12 to further transition the stiffnessof the catheter 10. As shown in FIG. 2, for example, a firstintermediate layer segment 52 can be provided about the inner layer 36along a portion of the proximal, intermediate, and distal shaft sections14,16,18, terminating distally at a location 54 proximal to the distalend 24 of the shaft 12. The first intermediate layer segment 52 maycomprise a polymeric material such as PEBAX® 5533 having an elasticitysufficient to permit the distal portion of the catheter 10 to radiallyflex or bend while providing additional column strength to withstandbuckling or kinking as the catheter 10 is tracked through the body. Thefirst intermediate layer segment 52 may further act as a tie layer incertain embodiments to facilitate bonding of the inner layer 36 with thevarious outer layer segments 38,40,42,48 of the shaft 12.

In some embodiments, a second intermediate layer segment 56 may beprovided about the inner layer 36 along a portion of the distal shaftsection 18, extending from location 54 to a second location 58 proximalto the distal end 24 of the catheter 10. In contrast to intermediatelayer segment 52 described above, the second intermediate layer segment56 may comprise a relatively flexible material such as PEBAX® 2533,which further aids in transitioning the stiffness along the length ofthe distal shaft section 18.

The wall thickness of the various shaft sections 14,16,18 may be reducedalong one or more sections of the shaft 12 to transition theflexibility, torqueability, and other desired characteristics of thecatheter 10. In certain embodiments, for example, the proximal shaftsection 14 may have a wall thickness in the range of about 0.01 to 0.02inches, and more specifically 0.015 inches, whereas the distal shaftsection 18 may have a smaller wall thickness in the range of about 0.004to 0.006 inches, and more specifically 0.0055 inches. To furthertransition the stiffness, the intermediate shaft section 16 may includea tapered section 60 wherein the profile of the catheter 10 transitionsfrom about 2.4 Fr. to about 1.7 Fr. If desired, a second tapered section62 can be provided along the distal shaft section 18 to further reducethe profile at the distal end 24 of the catheter 10.

A reinforcement member (e.g. a braid, weave, etc.) can be provided alongall or a portion of the shaft length, providing additional stiffness andtorsional rigidity to the catheter 10, if desired. The reinforcementmember may include a first coil segment comprising three wire coillayers 64 disposed along the length of the shaft 12 from a location ator near the strain relief member 34 to a location 66 along theintermediate shaft section 16. As shown in FIG. 2, the coil layers 64forming the first coil segment can be encased entirely within the outerlayers 38,42,48 of the proximal and intermediate shaft section 14,16.

A second coil segment comprising a single wire coil layer 68 may extenddistally from location 66 along the intermediate shaft section 16 to apoint at or near location 58 along the distal shaft section 18. Incontrast to the first coil segment, the second coil segment may have agreater amount of flexibility to facilitate bending or flexion of thedistal portion of the catheter 10 as it is advanced through tortuousanatomy. As with the wire coil layers 64 forming the first coil segment,the single wire coil layer 68 can be encased entirely within the outerlayers 40,48 of the intermediate and distal shaft sections 16,18.

While two coil segments are specifically depicted in the embodiment ofFIG. 2, it should be understood that a greater or lesser number of coilsegments can be provided, either continuously or at discrete intervalsalong the length of the shaft 12. Moreover, while the transition instiffness along the length of the shaft 12 can be accomplished byvarying the number of coil layers encased within the shaft 12, otherfactors such as the size of the coils employed, the material selection,and/or the pitch of the coils can also be varied to alter theperformance characteristics of the catheter 10. In the latter case, forexample, the coil pitch of the coils 68 forming the second coil segmentcan be made greater than the coil pitch of the coils 64 forming thefirst coil segment, thus imparting a greater amount of flexibility tothe distal portion of the catheter 10. The types of wire or wires (e.g.round, flat, etc.) used in forming the various coil segments may also bealtered to change the performance characteristics of the catheter 10, ifdesired. In certain embodiments, the selection of materials used to formeach of the coil segments can also be varied to impart a desiredflexibility to the catheter 10.

The catheter 10 may include one or more radiopaque features that permitthe device to be visualized within the body using a fluoroscope or othersuch device. In certain embodiments, for example, a distal radiopaquemarker 70 encased within the distal shaft section 18 can be provided topermit the physician to radiographically visualize the distal end 24 ofthe catheter 10 as it is advanced through the body. The distalradiopaque marker 70 may include a suitable material such as platinum,gold, or tantalum, or a combination of materials such asplatinum/iridium that can be used to radiographically determine thelocation of the catheter 10 within the vasculature. The distalradiopaque marker 70 should typically be placed at or near the distalend 24 of the shaft 12 to permit the physician to accurately determinethe location of the catheter tip. In some embodiments, for example, theradiopaque marker can be positioned at a location about 0.75 cm awayfrom the distal end 24 of the catheter 10. It should be understood,however, that other placement positions are possible.

In certain embodiments, the catheter 10 may further include a proximalradiopaque marker 72 encased with the distal shaft section 18 at alocation proximal to the distal radiopaque marker 70. In the treatmentof brain aneurisms, for example, such proximal radiopaque marker 72 canbe used to align the coil delivery wire used in many endovascularcoiling procedures. As with the distal radiopaque marker 70, theproximal radiopaque marker 72 can include a radiopaque material orcombination of radiopaque materials that provide sufficient contrast topermit fluoroscopic visualization. The placement location of theproximal radiopaque marker 72 will typically vary based on theparticular anatomy to be traversed, and the type of intravascular deviceto be inserted through the interior lumen 20. In endovascular coilingtechniques involving the neurovasculature, for example, the proximalradiopaque marker band 72 can be placed at a location of about 30 cmfrom the distal end 24 of the shaft 12, although other placementpositions are possible.

To further aid in visualization of the catheter 10 within the body, oneor more of the shaft sections 14,16,18 can be loaded or otherwiseinclude a radiopaque material. In certain embodiments, for example, theproximal, intermediate, and distal shaft sections 14,16,18 may be loadedwith tungsten (W), bismuth subcarbonate ((BiO₂)CO₃), barium sulfate(BaSO₄) or other suitable radiopaque agent. The amount of loading mayvary depending on the amount of radiopacity necessary to providesufficient visibility of the catheter 10 on a fluoroscopic monitor. Inembodiments employing a radiopaque filler of BaSO₄, for example, a 20%by weight concentration will typically provide sufficient visibility ofthe catheter 10 within the body. It should be understood, however, thatother factors such as the wall thickness and material composition of theshaft 12 can also affect the amount of loading necessary to providesufficient visibility.

In some embodiments, all or a portion of the outer surface of thecatheter 10 may include a lubricious coating that can be used tofacilitate tracking of the catheter 10 through the tortuous anatomyand/or beyond lesions or other obstructions within the body. Examples ofsuitable lubricous materials may include hydrophilic polymers such aspolyarylene oxides, polyvinylpyrolidones, polyvinylalcohols, hydroxyalkyl cellulsics, aligns, saccharides, caprolactones, and the like, ormixtures and combinations thereof. Lubricious materials such as thatdescribed above with respect to the inner layer or coating 36 can alsobe utilized, if desired.

The coated length along which the lubricious coating is applied to thecatheter 10 may vary depending on the overall length of the shaft 12. Inthose embodiments where the overall length of the catheter 10 isapproximately 150 cm, for example, the length of the lubricious coatingmay be provided on the distal-most 100 cm length of the shaft 12,providing additional lubricity to the leading portion of the catheter10. Conversely, in those embodiments where the overall length of thecatheter is approximately 130 cm and 105 cm, the length of thelubricious coating may be provided on a 97 cm and 72 cm length of theshaft 12, respectively, providing additional lubricity in thoseembodiments. The length and/or placement location of the lubriciouscoating may vary, however, depending on the performance characteristicsdesired in the catheter 10 as well as other factors.

The catheter 10 can include a number of pre-shaped tip configurationsthat can be used to facilitate tracking of the device through selectlocations within the vasculature. In some cases, such pre-shaped tipconfigurations may reduce the shape variability that often results fromshaping the tip manually in a clinical or surgical setting. Moreover,such pre-formed tip shapes may reduce the overall time required toperform the interventional procedure by obviating the need to shape thetip just prior to insertion within the patient's body.

FIG. 3 is a side plan view showing the catheter 10 of FIG. 1 equippedwith a distal tip section 74 in accordance with an illustrativeembodiment of the present invention having an angled tip configuration.As can be seen in FIG. 3, the distal tip section 74 of catheter 10 mayinclude a first straight section A of the shaft 12, a curved section Bof the shaft 12 extending distally of the first straight section A, anda second straight section C of the shaft 12 extending distally from thecurved section B.

The curved section B of the shaft 12 can be configured to orient thedistal end 24 at an angle θ₁ relative to a general longitudinal axis Lof the shaft 12. In certain embodiments, for example, the curved sectionB can be configured to orient the second straight section C at an angleθ₁ of about 25° to 65°, and more specifically 35° to 55° relative to thelongitudinal axis L. Angles θ₁ greater or lesser than these ranges canbe employed, however.

The distal end 24 of the catheter 10 can be located a distance D₁ awayfrom the outer periphery of the first straight section A, which, incertain embodiments, may represent the maximum profile of the distal tipsection 74. The angle θ₁ at which the second straight section C isoriented relative to the longitudinal axis L as well as the length ofthe second straight section C can be varied to permit the catheter 10 tobe used in particular locations of the patient's anatomy. Inneurological and peripheral interventions, for example, such dimensionscan be selected to form a distal tip section 74 having a profile (i.e.D₁ dimension) of approximately 0.22 inches, allowing the catheter 10 tobe easily inserted into difficult anatomy such as the anterior orposterior communicating artery.

FIG. 4 is a side plan view showing the catheter 10 of FIG. 1 equippedwith a distal tip section 76 in accordance with an illustrativeembodiment of the present invention having a curved tip configuration.As can be seen in FIG. 4, the distal tip section 76 of catheter 10 mayinclude a straight section D of the shaft 12, and a curved section E ofthe shaft 12 extending distally from the straight section D.

The curved section E of the shaft 12 can be configured to orient thedistal end 24 at an angle θ₂ relative to the general longitudinal axis Lof the catheter 10. In the illustrative embodiment depicted in FIG. 4,for example, the distal end 24 of the catheter 10 is shown oriented atangle θ₂ of approximately 90°. It should be understood, however, thatthe curved section E of the shaft 12 can be configured to orient thedistal end 24 at an angle θ₂ greater or lesser than 90°, if desired.

As with the embodiment of FIG. 3, the distal end 24 of the catheter 10can be located a distance D₂ away from the outer periphery of thestraight section D, which, in certain embodiments, may represent themaximum profile of the distal tip section 76. In one illustrativeembodiment, for example, the curved section E of the shaft 12 can beconfigured such that the distal end 24 is located a distance D₂ ofapproximately 0.22 inches away from the outer periphery of the straightsection D. Other configurations are, of course, possible.

FIG. 5 is a side plan view showing the catheter 10 of FIG. 1 equippedwith a distal tip section 78 in accordance with an illustrativeembodiment of the present invention having a J-shaped tip configuration.As can be seen in FIG. 5, the distal tip section 78 of catheter 10 mayinclude a first straight section F of the shaft 12, a curved section Gof the shaft 12 extending distally from the first straight section F,and a second straight section H of the shaft 12 extending distally fromthe curved section G.

In the illustrative embodiment of FIG. 5, the curved section G of theshaft 12 can be configured to orient the distal end 24 in a proximaldirection, forming a J-shaped portion of the catheter 10. The rise andrun of the curved section G may be defined generally by reference toangle θ₃, which defines the angle at which a tangent line intersects thecurved section G from a known point 80 along the longitudinal axis L. Incertain embodiments, for example, the curved section G may define anangle θ₃ of approximately 170°, orienting the distal end 24 of the shaft12 proximally a distance D₃ (e.g. 0.2 inches) away from the distal-mostportion of the curved section G.

FIG. 6 is a side plan view showing the catheter 10 of FIG. 1 equippedwith a distal tip section 82 in accordance with an illustrativeembodiment of the present invention having a C-shaped tip configuration.As can be seen in FIG. 6, the distal tip section 82 of catheter 10 mayinclude a first straight section I of the shaft 12, a first curvedsection J of the shaft 12 extending distally from the first straightsection I, a second straight section K of the shaft 12 extendingdistally from the first curved section J, and a second curved section Lof the shaft 12 extending distally from the second straight section K.

The first curved section J of the shaft 12 can be configured to orientthe second straight section K at an angle θ₄ relative to the generallongitudinal axis L of the catheter 10. The second curved section L ofthe shaft 12, in turn, can be configured to orient the distal end 24 atan angle θ₅ relative to the general longitudinal axis L. The variousangles θ₄, θ₅ and section lengths can be selected to form a C-shapedsection 84 having an overall length defined by dimension D₄, which inthe illustrative embodiment of FIG. 6 extends from the distal end of thefirst straight section I to the distal-most portion of the second curvedsection L. The particular length D₄ imparted to the distal tip section82 may vary depending on the intended use of the catheter 10. Inneurological and peripheral interventions, for example, the C-shapedsection 84 can be configured to have a length D₄ of about 0.5 inches,although other lengths are possible.

FIG. 7 is a side plan view showing the catheter 10 of FIG. 1 equippedwith a distal tip section 86 in accordance with an illustrativeembodiment of the present invention having an S-shaped tipconfiguration. As can be seen in FIG. 7, the distal tip section 86 ofcatheter 10 may include a first straight section M of the shaft 12, afirst curved section N of the shaft 12 extending distally from the firststraight section M, a second straight section O of the shaft 12extending distally from the first curved section N, a second curvedsection P of the shaft 12 extending distally from the second straightsection O, a third straight section Q of the shaft 12 extending distallyfrom the second curved section P, a third curved section R of the shaft12 extending distally from the third straight section Q, and a fourthstraight section S of the shaft 12 extending distally from the thirdcurved section R.

The first curved section N of the shaft 12 can be configured to orientthe second straight section O at an angle θ₆ away from the generallongitudinal axis L of the shaft 12. The second curved section P of theshaft 12, in turn, can be configured to orient the third straightsection Q at an angle θ₇ relative to the longitudinal axis L. Thedistance D₅ between the distal end of the first straight section M andthe portion of the third straight section Q crossing the longitudinalaxis L may define the first leg of an S-shaped portion 88 of the distaltip section 86.

As can be further seen in FIG. 7, the third curved section R may bendand orient the fourth straight section S of the shaft 12 at an angle θ₈relative to the third straight section Q, forming a second leg of theS-shaped section 88 having a length defined by distance D₆. The varioussection lengths and angles can also be selected such that length D₆ ofthe second leg is smaller than the length D₅ of the first leg. In oneillustrative embodiment, for example, the length D₆ of the second legcan be approximately 0.08 inches whereas the length D₅ of the first legcan be approximately 0.36 inches. Other configurations wherein thelength D₆ of the second leg is greater than or substantially equal tothe length D₅ of the first leg can also be employed, if desired. In someembodiments, the overall length (Le. D₅+D₆) of the S-shaped section 88can be approximately 0.44 inches.

To retain the shape of any of the above distal tip sections74,76,78,84,86 prior to use and/or during sterilization, a shaperetention mandrel can be inserted into the interior lumen 20 of thecatheter 10. As shown in FIG. 8, for example, a shape retention mandrel90 comprising a wire member 92 having a proximal end 94 and a distal end96 can be sized to fit within the interior lumen 20 of the catheter 10prior to shaping. In some embodiments, a handle grip 98 coupled to theproximal end 94 of the wire mandrel 90 can be provided to facilitateinsertion of the wire mandrel 90 into the catheter 10, if desired. Theshape retention mandrel 90 can be provided as part of a kit or packagingcontaining the sterilized catheter 10, or as a separate member that islater inserted into the catheter 10 by the physician.

Having thus described the several embodiments of the present invention,those of skill in the art will readily appreciate that other embodimentsmay be made and used which fall within the scope of the claims attachedhereto. Numerous advantages of the invention covered by this documenthave been set forth in the foregoing description. It will be understoodthat this disclosure is, in many respects, only illustrative. Changesmay be made in details, particularly in matters of shape, size andarrangement of parts without exceeding the scope of the invention.

1. A catheter comprising: an elongated tubular shaft having a proximalshaft section, an intermediate shaft section, a distal shaft section, alength, and an interior lumen extending through the length adapted toslidably receive a guidewire; wherein the elongated tubular shaftincludes an inner layer extending from a proximal end of the elongatedtubular shaft to a distal end of the elongated tubular shaft; whereinthe proximal shaft section includes a first outer layer segmentcomprising a relatively high durometer polymeric material, and thedistal shaft section includes a second outer layer segment comprising arelatively low durometer polymeric material; wherein the intermediateshaft section includes a third outer layer segment comprising apolymeric material having a durometer intermediate to the first outerlayer segment and the second outer layer segment, and a fourth outerlayer segment comprising a polymeric material having a durometerintermediate to the first outer layer segment and the second outer layersegment that is different from the third outer layer segment; whereinthe elongate tubular shaft further includes a first intermediate layersegment disposed between the inner layer and the first, second, third,and fourth outer layer segments and terminating distally at a firstlocation within the distal shaft section proximal to the distal end, anda second intermediate layer segment disposed between the inner layer andthe first, second, third, and fourth outer layer segments and extendingdistally from the first location to a second location proximal to thedistal end; and a distal tip section having a pre-shaped tipconfiguration.
 2. The catheter of claim 1, wherein the inner layerincludes a hydrophilic polymer.
 3. The catheter of claim 1, wherein thethird outer layer segment has a durometer greater than the fourth outerlayer segment.
 4. The catheter of claim 1, further comprising an outercoating of lubricious material disposed along all or a portion of theelongated tubular shaft.
 5. The catheter of claim 1, further comprisinga first radiopaque marker encased within the second outer layer segment.6. The catheter of claim 5, further comprising second radiopaque markerencased within the second outer layer segment proximal to the firstradiopaque marker.
 7. The catheter of claim 1, further comprising afirst coil segment comprising three wire coil layers disposed along thelength of the elongated tubular shaft from a first location at or nearthe proximal end to a second location along the intermediate shaftsection.
 8. The catheter of claim 7, wherein the first coil segment isentirely encased within the first, third, and fourth outer layersegments.
 9. The catheter of claim 7, further comprising a second coilsegment extending from the second location to a third location along thedistal shaft section proximal to the distal end.
 10. The catheter ofclaim 9, wherein the second coil segment is entirely encased within thesecond and fourth outer layer segments.
 11. The catheter of claim 9,wherein the second coil segment is more flexible than the first coilsegment.
 12. The catheter of claim 1, wherein the pre-shaped tipconfiguration comprises an angled tip configuration.
 13. The catheter ofclaim 12, wherein the distal tip section includes a first straightsection of the elongated tubular shaft, a curved section of theelongated tubular shaft extending distally of the first straightsection, and a second straight section of the elongated tubular shaftextending distally from the curved section; wherein the curved sectionis configured to orient the distal end of the elongated tubular shaft atan angle of about 35 degrees to about 55 degrees relative to alongitudinal axis of the elongated tubular shaft.
 14. The catheter ofclaim 1, wherein the pre-shaped tip configuration comprises a J-shapedtip configuration.
 15. The catheter of claim 14, wherein the distal tipsection includes a first straight section of the elongated tubularshaft, a curved section of the elongated tubular shaft extendingdistally of the first straight section, and a second straight section ofthe elongated tubular shaft extending distally from the curved section;wherein the curved section is configured to orient the distal end of theelongated tubular shaft in a proximal direction such that the distal endis disposed proximally of a distal-most portion of the curved section.16. The catheter of claim 1, wherein the pre-shaped tip configurationcomprises a C-shaped tip configuration.
 17. The catheter of claim 16,wherein the distal tip section includes a first straight section of theelongated tubular shaft, a first curved section of the elongated tubularshaft extending distally of the first straight section, a secondstraight section of the elongated tubular shaft extending distally fromthe first curved section, and a second curved section of the elongatedtubular shaft extending distally from the second straight section;wherein the distal tip section is configured to orient the distal endtoward the proximal end at an oblique angle to a longitudinal axis ofthe elongated tubular shaft.
 18. The catheter of claim 1, wherein thepre-shaped tip configuration comprises an S-shaped tip configuration.19. The catheter of claim 18, wherein the distal tip section includes afirst straight section of the elongated tubular shaft, a first curvedsection of the elongated tubular shaft extending distally of the firststraight section, a second straight section of the elongated tubularshaft extending distally from the first curved section, a second curvedsection of the elongated tubular shaft extending distally from thesecond straight section, a third straight section extending distallyfrom the second curved section, a third curved section extendingdistally from the third straight section, and a fourth straight sectionextending distally from the third curved section; wherein the distal tipsection is configured such that the third straight section crosses alongitudinal axis of the elongated tubular shaft and the fourth straightsection crosses the longitudinal axis such that the distal end isdisposed on an opposite side of the longitudinal axis from the thirdcurved section and is oriented non-parallel to the longitudinal axis.20. The catheter of claim 1, wherein the pre-shaped tip configurationcomprises a curved tip configuration; wherein the distal tip sectionincludes a first straight section of the elongated tubular shaft and acurved section of the elongated tubular shaft extending distally of thefirst straight section; wherein the curved section is configured toorient the distal end of the elongated tubular shaft at an angle ofapproximately 90 degrees to a longitudinal axis of the elongated tubularshaft.